It has been established in the scientific literature that the elevation of growth hormone (GH) levels in mammals upon administration of GH-releasing compounds can lead to enhanced body weight and to enhanced milk production if suffictently elevated GH levels occur upon administration. Further, it is known that the elevation of growth hormone levels in mammals can be accomplished by application of known growth hormone releasing agents, such as the naturally occurring growth hormone releasing hormones.
The elevation of growth hormone levels in mammals can also be accomplished by application of growth hormone releasing peptides, some of which have been previously described, for example, by F. A. Momany in U.S. Pat. No. 4,223,019, U.S. Pat. No. 4,223,020, U.S. Pat. No. 4,223,021, U.S. Pat. No. 4,224,316, U.S. Pat. No. 4,226,857, U.S. Pat. No. 4,228,155, U.S. Pat. No. 4,228,156, U.S. Pat. No. 4,228,157, U.S. Pat. No. 4,228,158, U.S. Pat. No. 4,410,512 and U.S. Pat. No. 4,410,513.
Antibodies to the endogenous growth hormone release inhibitor, somatostatin (SRIF) have also been used to cause elevated GH levels. In this latter example, growth hormone levels are elevated by removing the endogenous GH-release inhibitor (SRIF) before it reaches the pituitary, where it inhibits the release of GH.
Each of these methods for promoting the elevation of growth hormone levels involve materials which are expensive to synthesize and/or isolate in sufficient purity for administration to a target animal. Short chain, relatively simple polypeptides which have the ability to promote the release of growth hormone would be desirable because they should be readily and inexpensively prepared, easily modified chemically and/or physically, as well as readily purified and formulated; and they should have excellent transport properties.